The present invention is directed to new diagnostic agents, and methods of use of such agents, for medical imaging using positron emission tomography (PET). PET is a nuclear medicine imaging technique which produces a three dimensional image of the body. PET imaging is commonly used to obtain non-invasive information about internal body structures and tissues and the function and health of such structures and tissues. PET uses a metabolically active molecule and a short-lived radioactive tracer isotope (to radiolabel the active molecule) as a diagnostic agent. The isotope decays by emitting a positron. When a PET diagnostic agent is administered to the body, it is retained or accumulates in certain tissues of interest, thereby facilitating imaging of those tissues based upon detection of gamma ray photons produced upon annihilation of positrons emitted from the radiolabeled PET diagnostic agent. Such annihilation occurs when an emitted positron collides with an electron present in the vicinity of emission, resulting in production of two 511 keV photons that are emitted in nearly opposite directions. Typically, such PET diagnostic agents are radiolabeled with (i.e., contain) one or more atoms that exhibit positron emission (such as certain isotopes of carbon, nitrogen, oxygen, fluorine, or rubidium, including 11C, 13N, 15O, 18F, and 82Rb). The effects of the emitted positrons (i.e., the subsequently emitted gamma ray photons) are detected by a detection device located outside the body which typically converts raw data into two- or three-dimensional images of the region of interest. The results are then read by a nuclear medicine physician or radiologist to interpret the results in terms of the patient's diagnosis and treatment.
Considerable effort has been invested in development of PET diagnostic agents in an effort to improve contrast between various anatomical features, such as between cancerous and non-cancerous tissues. Continued progress in medical science mandates improved options in such diagnostic capability, which in turn mandates further development of improved diagnostic agents.
Therefore, it is one object of the present invention to meet these characteristics, to overcome the drawbacks in prior methods and agents and to provide an improvement over these prior methods and agents.